Why Choose Struct Over Class?

Question

Playing around with Swift, coming from a Java background, why would you want to choose a Struct instead of a Class? Seems like they are the same thing, with a Struct offeri

Answer 1

Here are some other reasons to consider:

1. structs get an automatic initializer that you don't have to maintain in code at all.

   struct MorphProperty {
      var type : MorphPropertyValueType
      var key : String
      var value : AnyObject
   
      enum MorphPropertyValueType {
          case String, Int, Double
      }
    }
   
    var m = MorphProperty(type: .Int, key: "what", value: "blah")
   

To get this in a class, you would have to add the initializer, and maintain the intializer...

2. Basic collection types like Array are structs. The more you use them in your own code, the more you will get used to passing by value as opposed to reference. For instance:

   func removeLast(var array:[String]) {
      array.removeLast()
      println(array) // [one, two]
   }
   
   var someArray = ["one", "two", "three"]
   removeLast(someArray)
   println(someArray) // [one, two, three]
   

3. Apparently immutability vs. mutability is a huge topic, but a lot of smart folks think immutability -- structs in this case -- is preferable. Mutable vs immutable objects